1. Field of the Invention
The present invention relates to sound detection and more particularly to a method and apparatus for detecting transient acoustical events in the presence of background noise. The invention further relates to the detection of transient acoustical events underwater.
2. Related Technical Art
It is often desirable to determine if a series of acoustical elements or an acoustical pattern represents a transient acoustical event. That is, it is desirable to detect the presence of sound producing machines or mechanisms in a particular environment in order to determine if the event is of some significance to a given detection system or observer. Such a determination often needs to be made in the presence of substantial acoustical interference or background noise.
One very desirable application for this technology is in ship board detection systems which detect approaching ships or torpedoes in order to take appropriate defensive measures or countermeasures. It is well understood that it is necessary to obtain sufficiently advanced warning of potential threats such as torpedoes in order to perform adequate evasive or countermeasure action. While some equipment exists for detecting sounds in an observer's general surroundings, it is very difficult to detect short term, faint, sounds in the presence of significant background noise which also includes observer generated noise.
Current detection systems operate by selectively amplifying and filtering acoustical elements within predetermined spectral ranges to provide assistance to a human observer. However, this technique relies on extensive intervention by a human operator, the reliability of which decreases with increases in operator distraction and fatigue, both of which are present under many operating conditions. In addition, this technique does not adequately discriminate between transients and general background noise.
What is needed is an improved method of detecting the presence of true transient events in the midst of background noise with decreased operator involvement. The method would be more useful if high speed digital processing for later threat analysis can be incorporated along with highly automated alarm signaling capabilities.